feat(ui): page header actions — Edit (accent) + Revisions menu (view/restore) + Export, top-right

Editor refactored to expose controls; Edit moved into the doc header as the orange
primary action; new Revisions dropdown lists page_revisions with a modal preview + Restore.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

public/components/revisions_menu.js

@@ -0,0 +1,57 @@
+// Revisions dropdown for a page: lists page_revisions; clicking one opens a modal
+// with the rendered old content + a Restore action (PATCH body_md).
+import { el } from '../dom.js';
+import { api } from '../api.js';
+import { marked } from '../vendor/marked.esm.js';
+import DOMPurify from '../vendor/purify.es.mjs';
+
+export function revisionsMenu(pageId, onRestore) {
+  const wrap = el('div', { class: 'exp-menu' });
+  const list = el('div', { class: 'exp-list rev-list' });
+
+  const btn = el('button', {
+    class: 'ghost',
+    onclick: async (e) => { e.stopPropagation(); if (wrap.classList.toggle('open')) await load(); }
+  }, 'Revisions ▾');
+
+  async function load() {
+    list.replaceChildren(el('div', { class: 'muted', style: { padding: '7px 10px' } }, 'Loading…'));
+    let revs = [];
+    try { revs = await api.get('/api/pages/' + pageId + '/revisions'); } catch { /* */ }
+    list.replaceChildren();
+    if (!revs.length) { list.appendChild(el('div', { class: 'muted', style: { padding: '7px 10px' } }, 'No earlier revisions.')); return; }
+    revs.forEach(r => list.appendChild(el('button', { onclick: () => view(r) },
+      new Date(r.created_at).toLocaleString() + (r.edited_by ? ` · ${r.edited_by}` : ''))));
+  }
+
+  function view(rev) {
+    wrap.classList.remove('open');
+    const body = el('div', { class: 'md-preview' });
+    body.innerHTML = DOMPurify.sanitize(marked.parse(rev.body_md || ''));
+    const modal = el('div', {
+      class: 'rev-overlay',
+      onclick: (e) => { if (e.target === modal) modal.remove(); }
+    },
+      el('div', { class: 'rev-modal' },
+        el('div', { class: 'rev-modal-head' },
+          el('span', {}, 'Revision · ' + new Date(rev.created_at).toLocaleString()),
+          el('button', { class: 'ghost', onclick: () => modal.remove() }, 'Close')),
+        body,
+        el('div', { class: 'rev-modal-foot' },
+          el('button', {
+            class: 'primary',
+            onclick: async () => {
+              try {
+                await api.patch('/api/pages/' + pageId, { body_md: rev.body_md });
+                if (onRestore) onRestore(rev.body_md);
+                modal.remove();
+              } catch (e) { alert('Restore failed: ' + e.message); }
+            }
+          }, 'Restore this version'))));
+    document.body.appendChild(modal);
+  }
+
+  wrap.append(btn, list);
+  document.addEventListener('click', () => wrap.classList.remove('open'));
+  return wrap;
+}